Composite substrate for rechargeable lithium battery and rechargeable lithium battery including the same

Abstract

Disclosed are composite substrates and rechargeable lithium batteries. The composite substrate includes a support layer, a first metal layer on a top surface of the support layer, and a second metal layer on a bottom surface of the support layer. At least one of the first metal layer and the second metal layer includes a first region to which a tab is configured to be attached, and a second region different from the first region. A ratio of surface roughness of the first region to surface roughness of the second region is in a range of about 3.5 to about 7.

What is claimed is: 
     
         1 . A composite substrate for a rechargeable lithium battery, the composite substrate comprising:
 a support layer;   a first metal layer on a top surface of the support layer; and   a second metal layer on a bottom surface of the support layer,   wherein at least one of the first metal layer and the second metal layer includes:
 a first region to which a tab is configured to be attached; and 
 a second region different from the first region, 
   wherein a ratio of surface roughness of the first region to surface roughness of the second region is in a range of about 3.5 to about 7.   
     
     
         2 . The composite substrate of  claim 1 , wherein the surface roughness of the first region is in a range of about 1 μm to about 3 μm. 
     
     
         3 . The composite substrate of  claim 1 , wherein the surface roughness of the second region is in a range of about 0.1 μm to about 0.5 μm. 
     
     
         4 . The composite substrate of  claim 1 , wherein a width of the first region is in a range of about 5 mm to about 30 mm. 
     
     
         5 . The composite substrate of  claim 1 , wherein the surface roughness of the first region is greater than the surface roughness of the second region. 
     
     
         6 . The composite substrate of  claim 1 , wherein the support layer comprises at least one of a polyethylene film, a polypropylene film, a polyvinylidene chloride film, and a multi-layered film including a combination thereof. 
     
     
         7 . The composite substrate of  claim 1 , wherein at least one of the first and second metal layers comprises at least one of aluminum, aluminum alloys, copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, iron, iron alloys, silver, and silver alloys. 
     
     
         8 . The composite substrate of  claim 1 , wherein:
 a thickness of at least one of the first and second metal layers is in a range of about 200 nm to about 5 μm, and   a thickness of the support layer is in a range of about 3 μm to about 10 μm.   
     
     
         9 . The composite substrate of  claim 1 , further comprising a tab attached to the first region of the at least one of the first and second metal layers,
 wherein the first region includes a first recess in which the tab is buried.   
     
     
         10 . The composite substrate of  claim 9 , wherein the tab comprises:
 a first portion buried in the first recess; and   a second portion on the first portion,   wherein a thickness of the second portion is less than a thickness of the first portion.   
     
     
         11 . A rechargeable lithium battery, comprising:
 a composite substrate that includes a support layer and a metal layer on the support layer; and   a battery cell on the metal layer,   wherein the metal layer includes:
 a first region to which a tab is configured to be attached; and 
 a second region different from the first region, 
   wherein a ratio of surface roughness of the first region to surface roughness of the second region is in a range of about 3.5 to about 7.   
     
     
         12 . The rechargeable lithium battery of  claim 11 , wherein the battery cell comprises:
 a first active material layer on the metal layer;   a separator on the first active material layer;   a second active material layer on the separator; and   a metal substrate on the second active material layer.   
     
     
         13 . The rechargeable lithium battery of  claim 12 , further comprising:
 a first tab attached to the metal layer; and   a second tab attached to the metal substrate,   wherein the metal layer includes a first recess that is recessed by the first tab,   wherein the metal substrate includes a second recess that is recessed by the second tab, and   wherein a depth of the first recess is greater than a depth of the second recess.   
     
     
         14 . The rechargeable lithium battery of  claim 13 , wherein a ratio of the depth of the first recess to the depth of the second recess is in a range of about 2 to about 100. 
     
     
         15 . The rechargeable lithium battery of  claim 13 , wherein:
 the first tab includes a first portion buried in the first recess,   the second tab includes a second portion buried in the second recess, and   a thickness of the first portion is greater than a thickness of the second portion.   
     
     
         16 . The rechargeable lithium battery of  claim 11 , wherein:
 the support layer includes at least one of a polyethylene film, a polypropylene film, a polyvinylidene chloride film, and a multi-layered film including a combination thereof, and   the metal layer includes at least one of aluminum, aluminum alloys, copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, iron, iron alloys, silver, and silver alloys.   
     
     
         17 . The rechargeable lithium battery of  claim 11 , wherein:
 a thickness of the metal layer is in a range of about 200 nm to about 5 μm, and   a thickness of the support layer is in a range of about 3 μm to about 10 μm.   
     
     
         18 . A rechargeable lithium battery, comprising:
 a composite substrate that includes a support layer and a metal layer on the support layer;   a first active material layer on the metal layer;   a separator on the first active material layer;   a second active material layer on the separator;   a metal substrate on the second active material layer;   a first tab attached to the metal layer; and   a second tab attached to the metal substrate,   wherein the metal layer includes a first recess that is recessed by the first tab,   wherein the metal substrate includes a second recess that is recessed by the second tab, and   wherein a depth of the first recess is greater than a depth of the second recess.   
     
     
         19 . The rechargeable lithium battery of  claim 18 , wherein a ratio of the depth of the first recess to the depth of the second recess is in a range of about 2 to about 100. 
     
     
         20 . The rechargeable lithium battery of  claim 18 , wherein
 the first tab includes a first portion buried in the first recess,   the second tab includes a second portion buried in the second recess, and   a thickness of the first portion is greater than a thickness of the second portion.